1. Field of Invention
The invention relates to compatible polymer blends of polyphenylene ether and copolymers of (meth)acrylates with phenyl groups in the side chains.
2. Discussion of the Background
Empirical experience with experiments mixing different polymers has already been reduced to the much quoted common denominator: "Miscibility is the exception; immiscibility is the rule". (Cf. Kirk-Othmer, 3rd edition, vol. 18, pp. 443-478, 460 ff, J. Wiley 1982).
Such an exception is, for example, e.g., the compatible system of polyphenylene ether (PPE) and polystyrene (PS). PPE/PS blends exhibit one glass temperature over the entire mixing range and are transparent. They represent one of the first examples known in the literature of compatible polymer blends. (Cf. T. K. Kwei, H. L. Frisch, Macromolecules, 11:1267 (1978); Kirk-Othmer, loc. cit., Vol. 16, 594-605, 603 ff). Poly-2,6-dimethyl-1,4-phenylene oxides (DMPPO) and polystyrene form other compatible polymer blends (cf. S. Krause, J. Macromol. Sci. Rev. Macromol. Chem. 7:251 (1972); Brandrup-Immergut, Polymer Handbook, 3rd edition, VI-347, J. Wiley (1989).
Starting from this knowledge, a number of studies have analyzed the impact modification of brittle PPE with elastomer phases, which were grafted with PS or styrene copolymers. Preferably block polymers such as polystyrene-b-polybutadiene, ABS-terpolymers and SAN--grafted elastomer phases are added as impact modifiers.
A fundamental drawback of pure PPE and the aforementioned mixtures is the extreme instability with respect to UV and visible light with the consequence of a notorious instability under weathering conditions. Thus, for example, as a commercial product, a PPE/polyamide blend shows a noticeable yellow tinge and a dull surface after 500 hours of the Xenotest-accelerated weathering test. Polyaryl(meth)acrylates have proven to be compatible with polycarbonates (DE-A 37 19 239) and polyesters (German patent application P 40 03 088.1).